Binocular vision disorder is an inability of a person to fuse the two images from his or her two eyes into one coherent image (binocular combination) and/or to get a Three-Dimensional (3-D) dimensional view with depth perception (stereo acuity). Binocular vision disorder is especially common among amblyopia and strabismus patients but it is not limited to amblyopia and strabismus patients.
FIG. 1 is an illustration of normal binocular vision and binocular vision disorder. When presented with slide 101 at the left eye and slide 102 at the right eye, a person with healthy binocular vision will see image 103, which is a combined 2-D image. By contrast, a person who has binocular vision disorder may see image 104, which is improperly combined (in this case, not aligned).
When presented with slides 110 and 111 (which look similar but are slightly different so as to give a stereo 3-D effect), a person with healthy binocular vision will correctly perceive the 3-D quality of combined image 112. On the other hand, a person with binocular vision disorder will not correctly perceive the combined image as 3-D.
Most studies focus on monocular deficits in the amblyopic eye. Most amblyopia treatment products are for treating amblyopia in spatial vision for improvement of visual acuity, spatial frequency and contrast sensitivity. For stroke patient recovery, treatment tends to focus on motor exercise. There is a general lack of treatment for binocular vision capability.
One conventional technique for treating binocular vision capability includes the synoptophore. When using a synoptophore, a patient rests his or her head in the device, aligned with two viewing apparatuses—one for each eye. A healthcare worker manually inserts slides into the viewing portions to show each eye a different image. Prisms may be used to change a viewing angle at an eye or to change an optical axis relative to a geometric axis. The patient attempts to combine the images into either a 2-D image or a 3-D image. The synoptophore can be used to diagnose binocular vision disorder by giving the healthcare worker an indication of the disability. For instance, people with normal vision will see the fused image without changing the viewing angle to a large extent, but eye patients may require the help of adjusting the viewing angle by the synoptophore in order to see the fused image. Additionally or alternatively, the healthcare worker can use the synoptophore to treat the disability. In one example, the healthcare worker applies a regimen to train the patient's eyes and mind to perform binocular capability and to see in true 3-D. The regimen may include showing a series of slides, and perhaps adjusting an angle of view or a geometrical axis of the slides, to gradually acclimate the patient to binocular combination and 3-D viewing.
Synoptophores are not an optimal device for treatment and diagnosis. Synoptophores are table-top instruments that are fairly large and heavy. Thus, synoptophores are not portable, and a patient must travel to a clinic for treatment, perhaps several times a week. Furthermore, synoptophores are expensive and almost completely manual.